Abstract
A macroarray platform was used to identify binding sites of yeast histone acetyltransferase catalytic subunits and to correlate their positions with acetylation of lysine 14 of histone H3, revealing that Sas3p and Gcn5p are recruited to similar sets of intensely transcribed genes.
Highlights
Specific histone modifications can perform several cellular functions, for example, as signals to recruit trans-acting factors and as modulators of chromatin structure
Among the 275 tRNA genes, we focused on the 179 tRNA genes that are at less than 400 bp from an open reading frames (ORFs) because intergenic regions (IGRs) in yeast showed a distribution with a maximum at lengths from 150 to 800 bp (Figure 1)
Sas3p occupancies were plotted as a function of Gcn5p occupancies and a correlation coefficient (r) of 0.91 was obtained. Indicating that both histone acetyltransferases (HATs) are recruited to similar active genes. This finding is important because Sas3p, the catalytic subunit of NuA3 HAT complex [38], has been implicated in transcriptional silencing [39] and our results provide the first evidence that Sas3p could act as a transcriptional activator, like Gcn5p
Summary
Specific histone modifications can perform several cellular functions, for example, as signals to recruit trans-acting factors and as modulators of chromatin structure. Histones are subjected to a wide variety of post-translational modifications, most of them reversible [1,2], that can influence chromatin functions by different mechanisms This epigenetic information, composed of histone modifications, has been called the histone code [3,4,5,6] and can be considered as specific binding surfaces for the recruitment of activators or repressors of Genome Biology 2007, 8:R119. The existence of the histone code does not exclude the hypothesis that several histone modifications may directly affect the nucleosomal structure or the folding properties of the chromatin, facilitating the action of the protein complexes that regulate expression, repair, recombination and other essential functions of the eukaryotic genome. The SAS complex, which is composed of the Sas2p acetylase bound to the Sas and Sas proteins, acetylates free H3 at Lys14 [19], its specificity for nucleosomeassembled histones seems to be limited to H4 [20]
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